This invention relates to electrical connectors which house contacts associated with plug blades or contacts to which plug blades are admitted by apertures in the housing.
Merely as a representative example of a connector which may be improved in accordance with the present invention reference is made to copending application Ser. No. 631,356, filed July 16, 1984 by Pudims and assigned to the present assignee now U.S. Pat. No. 4,556,273 issued Dec. 3, 1985, which is herein incorporated by reference for its general description of such connectors. It will be apparent from the following discussion that the invention is generally applicable to connectors that may be characterized as having an insulating body, of one or more parts, with a plurality of electrical contacts supported therein and with terminal means for attaching conductors to it. An insulating cover is disposed over the body and has a circular aperture for accommodating an electrical line cord containing the conductors attached to the terminal means in the body. The terminal means may be associated with plug blades or with internal female contacts for receiving plug blades.
The practice has been to have the circular aperture for the line cord in the cover set in the original manufacture of the cover to accommodate the largest size line cord contemplated for use with that particular connector. This necessarily leads to some proliferation of covers with different size line cord apertures. Several cord sizes, for example, are used in the industrial and commercial applications of particular interest for application of the present invention. These sizes range from that designated 18-3SJ, which has a diameter of 0.3 inch to 12-3S, which has a diameter of 0.655 inch. If a connector is made with a cover whose original cord aperture can receive the 12-3S cord size, it is clear that there is going to be a wide gap between the edge of that aperture in the cover and the smallest cord size which has less than half the diameter. Such gaps are considered in the trade to be detrimental to long-life performance because of greater chance for the entry of dirt and other contaminants and are also unsightly. Sometimes a flexible ring is disposed on the cover rim to help close the gap but this necessitates an additional element to be assembled with the product, which would preferably be avoided for economic reasons.
It is recognized that in other electrical products such as switch boxes or wiring boxes, it is sometimes the case that a housing member, usually metal, is adapted for receipt of electrical conductors by the use of "knockouts". A knockout is a portion of the housing wall that can be removed by a user to form an opening for a conductor. Sometimes concentrically arranged knockouts are provided so the user can select from them to form a desired size opening in that location. What has not been previously known is an electrical connector of the character above described in which there is easy means for a user to modify a cord aperture from that originally provided to one accommodating a larger size cord, and to do so in a manner so that the connector is not subject to having the cord aperture inadvertently changed by breakage and with materials and dimensions that lend themselves to economical, quantity production with high reliability.
By the present invention, an insulating cover for a connector is configured so as to receive, at the user's option, two or more different cord sizes. The cover is a unitary molded member of insulating material so that the additional features of this invention do not appreciably complicate the manufacturing operation or add to its expense as compared to former connector covers. As originally manufactured, the cover is configured with an aperture that has a removable circular ring at its periphery. The removable ring and the remaining portion of the cover have a fracturable joint between them consisting of a region of insulating material with a thickness that is substantially less than that of the major portion of the ring. The arrangement is such that a user may use the cover for a cord that is accommodated by the original aperture size or he may readily remove the removable ring for enlarging the aperture to accommodate a larger size line cord. The removal of the ring is very simply performed by forcing the blade of a tool such as a screw driver into a groove on the exterior of the cover between the ring and the rest of the cover right at the fracturable joint of the ring and the remaining portion of the cover. Alternatively, a screwdriver blade or the like may be inserted within the central aperture so that its extremity is on the underside of one part of the ring while another portion of the blade is on the exterior of another part of the ring. A prying motion of the blade results in the fracture of the joint and separation of the ring from the rest of the housing cover.
The material of the cover is suitably selected from the group consisting of polycarbonate material and polyphenylene oxide material because these materials have a combination of good qualities in terms of dimensional stability, non-hygroscopic characteristics, good impact strength, and good temperature rating without being too brittle. The invention may also be practiced with other molded plastic materials.
The above and other aspects of the invention will be better understood by reference to the following description and the accompanying drawing.